It is one of most common ligament injury. Is usually develops when ankle gets twisted.

Ligaments are soft tissue structures which connect bones together and stabilize the joint. Sprain occurs when ligaments are forced beyond their normal range.

Symptoms
Pain in ankle
Swelling
Difficulty in walking or standing
Bruises
Risk Factors
Sports like basketball, football, tennis, running
Walking or running on uneven surfaces
Previous ankle injury
Improper shoes

Bones in children are softer and periosteum is thicker. so most of fractures in children are incomplete fractures, they are Greenstick fractures or torus fractures.

Greenstick Fractures
These involve bend on one side and fracture on another side of bone. It resembles bending of newly grown branch of a tree.
Torus Fractures
They are fracture in metaphyseal area of bone. usually develops due to longitudibal force e.g. Fall on outstretched hand.
Common Fractures in Children

Distal Radius Fracture: It is most common fracture in children.
Supracondylar Humerus fracture: It usually develops due to fall on outstretched hand